Plant cells contain many useful molecules, such as sugars and starches. Plant-derived sugars and starches are used in the food industry, for example, as sweeteners or as thickening agents. Plant-derived sugars and starches are also increasingly being used as starting materials in the production of renewable liquid fuels (i.e., biofuels), including methanol, ethanol, and butanol.
Generally, plant materials are subjected to numerous pre-treatment steps in order to facilitate the extraction of the useful molecules from the intact plant cell. For example, when sugar beets (i.e., Beta vulgaris) are used as a biofuel starting material or as a source of sucrose (i.e., table sugar), conventional pre-treatment steps include washing the beets to remove soil and micro-organism contaminants, such as the bacteria originating from the soil in which the beets were grown. The washed beets are then chipped or sliced in conventional cutting machines. The resulting sliced or chipped beets are scalded in hot water (i.e., between about 70° C. and about 75° C.). During this procedure, the beet cell walls are thermally denatured such that the cell walls are disrupted and become permeable to the sucrose molecules. A sucrose-containing juice is then obtained by extraction of the scalded beet material at temperatures of approximately 68° C. to 70° C.
A substantial amount of added water is needed to make the above-described extraction effective. Further, significant energy costs are accrued to effect the heating needed for both the thermal denaturation of the chipped or sliced beets and the full extraction of the juice.
Given for example the increasing importance of plant-derived ethanol, improvements to the conventional process are highly desirable. For example, processes that simplify the pre-fermentation or pre-extraction handling of sugar- and starch-containing plant materials are needed to reduce the cost, the water and/or energy usage, and the time requirements associated with conventional processes. Also of interest are improved processes that lead to an increase in the yield of products, such as alcohol, obtained from a given amount of raw plant material.